With the arrival of an advanced information society, the necessity of a data center is increasing more and more. In the data center, a large number of racks are installed in a room, and electronic devices such as, for example, servers or storage devices are accommodated in the respective racks so that these electronic devices are collectively managed.
Incidentally, as the performance of electronic devices has been improved, the calorific values of the electronic devices have been increased. When electronic devices having a large calorific value are mounted at a high density, the temperature of the electronic devices exceeds the allowable upper limit temperature, which causes malfunctions, failures, or a reduction in processing capability. Therefore, there is a demand for a cooling method that is capable of sufficiently cooling electronic devices having a large calorific value even if the electronic devices are mounted at a high density.
As the cooling method, it has been proposed to cool an electronic device by immersing the electronic device in a liquid coolant. Hereinafter, this type of cooling method is called an immersion cooling method. In the immersion cooling method, a liquid coolant (e.g., a fluorine compound), which is inert and has high insulation, is introduced into an immersion tank and an electronic device is immersed in the coolant so that the coolant circulates between the immersion tank and a heat exchanger.
In addition, a technique of cooling a room without using electricity by transporting heat of the room to the outside using a heat pipe has been proposed.
From the viewpoint of energy saving, a further reduction in electric power used in the data center is required. In the immersion cooling method, a pump consumes a relatively large amount of electric power because the pump is used to circulate the coolant between the immersion tank and the heat exchanger.
The followings are reference documents.
[Document 1] International Publication Pamphlet No. WO 2016/031781 and
[Document 2] Japanese Patent Laid-Open Publication No. 05-322459.